20621947 has 2 divisors, whose sum is σ = 20621948. Its totient is φ = 20621946.

The previous prime is 20621921. The next prime is 20621959. The reversal of 20621947 is 74912602.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20621947 is a prime.

It is not a weakly prime, because it can be changed into another prime (20621917) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10310973 + 10310974.

It is an arithmetic number, because the mean of its divisors is an integer number (10310974).

Almost surely, 2^20621947 is an apocalyptic number.

20621947 is a deficient number, since it is larger than the sum of its proper divisors (1).

20621947 is an equidigital number, since it uses as much as digits as its factorization.

20621947 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6048, while the sum is 31.

The square root of 20621947 is about 4541.1393944692. The cubic root of 20621947 is about 274.2267955483.

The spelling of 20621947 in words is "twenty million, six hundred twenty-one thousand, nine hundred forty-seven".